#include <stdio.h>
#include <stdlib.h>

int (*sum)(int left, int right);
int sum_impl(int, int);

typedef int(*sum_type)(int, int);

int main(int argc, char** argv){
	sum = &sum_impl;
	int result = sum(10, 20);
	printf("result: %d\n", result);

	sum_type function = &sum_impl;
	result = function(10, 30);
	printf("result: %d\n", result);
}

int sum_impl(int left, int right){
	return left + right;
}
